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sys/netgraph/ng_bridge.c

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    1 /*
    2  * ng_bridge.c
    3  */
    4 
    5 /*-
    6  * Copyright (c) 2000 Whistle Communications, Inc.
    7  * All rights reserved.
    8  * 
    9  * Subject to the following obligations and disclaimer of warranty, use and
   10  * redistribution of this software, in source or object code forms, with or
   11  * without modifications are expressly permitted by Whistle Communications;
   12  * provided, however, that:
   13  * 1. Any and all reproductions of the source or object code must include the
   14  *    copyright notice above and the following disclaimer of warranties; and
   15  * 2. No rights are granted, in any manner or form, to use Whistle
   16  *    Communications, Inc. trademarks, including the mark "WHISTLE
   17  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
   18  *    such appears in the above copyright notice or in the software.
   19  * 
   20  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
   21  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
   22  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
   23  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
   24  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
   25  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
   26  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
   27  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
   28  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
   29  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
   30  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
   31  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
   32  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
   33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   35  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
   36  * OF SUCH DAMAGE.
   37  *
   38  * Author: Archie Cobbs <archie@freebsd.org>
   39  *
   40  * $FreeBSD: stable/9/sys/netgraph/ng_bridge.c 249132 2013-04-05 08:22:11Z mav $
   41  */
   42 
   43 /*
   44  * ng_bridge(4) netgraph node type
   45  *
   46  * The node performs standard intelligent Ethernet bridging over
   47  * each of its connected hooks, or links.  A simple loop detection
   48  * algorithm is included which disables a link for priv->conf.loopTimeout
   49  * seconds when a host is seen to have jumped from one link to
   50  * another within priv->conf.minStableAge seconds.
   51  *
   52  * We keep a hashtable that maps Ethernet addresses to host info,
   53  * which is contained in struct ng_bridge_host's. These structures
   54  * tell us on which link the host may be found. A host's entry will
   55  * expire after priv->conf.maxStaleness seconds.
   56  *
   57  * This node is optimzed for stable networks, where machines jump
   58  * from one port to the other only rarely.
   59  */
   60 
   61 #include <sys/param.h>
   62 #include <sys/systm.h>
   63 #include <sys/kernel.h>
   64 #include <sys/lock.h>
   65 #include <sys/malloc.h>
   66 #include <sys/mbuf.h>
   67 #include <sys/errno.h>
   68 #include <sys/rwlock.h>
   69 #include <sys/syslog.h>
   70 #include <sys/socket.h>
   71 #include <sys/ctype.h>
   72 
   73 #include <net/if.h>
   74 #include <net/ethernet.h>
   75 #include <net/vnet.h>
   76 
   77 #include <netinet/in.h>
   78 #if 0   /* not used yet */
   79 #include <netinet/ip_fw.h>
   80 #endif
   81 #include <netgraph/ng_message.h>
   82 #include <netgraph/netgraph.h>
   83 #include <netgraph/ng_parse.h>
   84 #include <netgraph/ng_bridge.h>
   85 
   86 #ifdef NG_SEPARATE_MALLOC
   87 static MALLOC_DEFINE(M_NETGRAPH_BRIDGE, "netgraph_bridge",
   88     "netgraph bridge node");
   89 #else
   90 #define M_NETGRAPH_BRIDGE M_NETGRAPH
   91 #endif
   92 
   93 /* Per-link private data */
   94 struct ng_bridge_link {
   95         hook_p                          hook;           /* netgraph hook */
   96         u_int16_t                       loopCount;      /* loop ignore timer */
   97         struct ng_bridge_link_stats     stats;          /* link stats */
   98 };
   99 
  100 /* Per-node private data */
  101 struct ng_bridge_private {
  102         struct ng_bridge_bucket *tab;           /* hash table bucket array */
  103         struct ng_bridge_link   *links[NG_BRIDGE_MAX_LINKS];
  104         struct ng_bridge_config conf;           /* node configuration */
  105         node_p                  node;           /* netgraph node */
  106         u_int                   numHosts;       /* num entries in table */
  107         u_int                   numBuckets;     /* num buckets in table */
  108         u_int                   hashMask;       /* numBuckets - 1 */
  109         int                     numLinks;       /* num connected links */
  110         int                     persistent;     /* can exist w/o hooks */
  111         struct callout          timer;          /* one second periodic timer */
  112 };
  113 typedef struct ng_bridge_private *priv_p;
  114 
  115 /* Information about a host, stored in a hash table entry */
  116 struct ng_bridge_hent {
  117         struct ng_bridge_host           host;   /* actual host info */
  118         SLIST_ENTRY(ng_bridge_hent)     next;   /* next entry in bucket */
  119 };
  120 
  121 /* Hash table bucket declaration */
  122 SLIST_HEAD(ng_bridge_bucket, ng_bridge_hent);
  123 
  124 /* Netgraph node methods */
  125 static ng_constructor_t ng_bridge_constructor;
  126 static ng_rcvmsg_t      ng_bridge_rcvmsg;
  127 static ng_shutdown_t    ng_bridge_shutdown;
  128 static ng_newhook_t     ng_bridge_newhook;
  129 static ng_rcvdata_t     ng_bridge_rcvdata;
  130 static ng_disconnect_t  ng_bridge_disconnect;
  131 
  132 /* Other internal functions */
  133 static struct   ng_bridge_host *ng_bridge_get(priv_p priv, const u_char *addr);
  134 static int      ng_bridge_put(priv_p priv, const u_char *addr, int linkNum);
  135 static void     ng_bridge_rehash(priv_p priv);
  136 static void     ng_bridge_remove_hosts(priv_p priv, int linkNum);
  137 static void     ng_bridge_timeout(node_p node, hook_p hook, void *arg1, int arg2);
  138 static const    char *ng_bridge_nodename(node_p node);
  139 
  140 /* Ethernet broadcast */
  141 static const u_char ng_bridge_bcast_addr[ETHER_ADDR_LEN] =
  142     { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
  143 
  144 /* Store each hook's link number in the private field */
  145 #define LINK_NUM(hook)          (*(u_int16_t *)(&(hook)->private))
  146 
  147 /* Compare Ethernet addresses using 32 and 16 bit words instead of bytewise */
  148 #define ETHER_EQUAL(a,b)        (((const u_int32_t *)(a))[0] \
  149                                         == ((const u_int32_t *)(b))[0] \
  150                                     && ((const u_int16_t *)(a))[2] \
  151                                         == ((const u_int16_t *)(b))[2])
  152 
  153 /* Minimum and maximum number of hash buckets. Must be a power of two. */
  154 #define MIN_BUCKETS             (1 << 5)        /* 32 */
  155 #define MAX_BUCKETS             (1 << 14)       /* 16384 */
  156 
  157 /* Configuration default values */
  158 #define DEFAULT_LOOP_TIMEOUT    60
  159 #define DEFAULT_MAX_STALENESS   (15 * 60)       /* same as ARP timeout */
  160 #define DEFAULT_MIN_STABLE_AGE  1
  161 
  162 /******************************************************************
  163                     NETGRAPH PARSE TYPES
  164 ******************************************************************/
  165 
  166 /*
  167  * How to determine the length of the table returned by NGM_BRIDGE_GET_TABLE
  168  */
  169 static int
  170 ng_bridge_getTableLength(const struct ng_parse_type *type,
  171         const u_char *start, const u_char *buf)
  172 {
  173         const struct ng_bridge_host_ary *const hary
  174             = (const struct ng_bridge_host_ary *)(buf - sizeof(u_int32_t));
  175 
  176         return hary->numHosts;
  177 }
  178 
  179 /* Parse type for struct ng_bridge_host_ary */
  180 static const struct ng_parse_struct_field ng_bridge_host_type_fields[]
  181         = NG_BRIDGE_HOST_TYPE_INFO(&ng_parse_enaddr_type);
  182 static const struct ng_parse_type ng_bridge_host_type = {
  183         &ng_parse_struct_type,
  184         &ng_bridge_host_type_fields
  185 };
  186 static const struct ng_parse_array_info ng_bridge_hary_type_info = {
  187         &ng_bridge_host_type,
  188         ng_bridge_getTableLength
  189 };
  190 static const struct ng_parse_type ng_bridge_hary_type = {
  191         &ng_parse_array_type,
  192         &ng_bridge_hary_type_info
  193 };
  194 static const struct ng_parse_struct_field ng_bridge_host_ary_type_fields[]
  195         = NG_BRIDGE_HOST_ARY_TYPE_INFO(&ng_bridge_hary_type);
  196 static const struct ng_parse_type ng_bridge_host_ary_type = {
  197         &ng_parse_struct_type,
  198         &ng_bridge_host_ary_type_fields
  199 };
  200 
  201 /* Parse type for struct ng_bridge_config */
  202 static const struct ng_parse_fixedarray_info ng_bridge_ipfwary_type_info = {
  203         &ng_parse_uint8_type,
  204         NG_BRIDGE_MAX_LINKS
  205 };
  206 static const struct ng_parse_type ng_bridge_ipfwary_type = {
  207         &ng_parse_fixedarray_type,
  208         &ng_bridge_ipfwary_type_info
  209 };
  210 static const struct ng_parse_struct_field ng_bridge_config_type_fields[]
  211         = NG_BRIDGE_CONFIG_TYPE_INFO(&ng_bridge_ipfwary_type);
  212 static const struct ng_parse_type ng_bridge_config_type = {
  213         &ng_parse_struct_type,
  214         &ng_bridge_config_type_fields
  215 };
  216 
  217 /* Parse type for struct ng_bridge_link_stat */
  218 static const struct ng_parse_struct_field ng_bridge_stats_type_fields[]
  219         = NG_BRIDGE_STATS_TYPE_INFO;
  220 static const struct ng_parse_type ng_bridge_stats_type = {
  221         &ng_parse_struct_type,
  222         &ng_bridge_stats_type_fields
  223 };
  224 
  225 /* List of commands and how to convert arguments to/from ASCII */
  226 static const struct ng_cmdlist ng_bridge_cmdlist[] = {
  227         {
  228           NGM_BRIDGE_COOKIE,
  229           NGM_BRIDGE_SET_CONFIG,
  230           "setconfig",
  231           &ng_bridge_config_type,
  232           NULL
  233         },
  234         {
  235           NGM_BRIDGE_COOKIE,
  236           NGM_BRIDGE_GET_CONFIG,
  237           "getconfig",
  238           NULL,
  239           &ng_bridge_config_type
  240         },
  241         {
  242           NGM_BRIDGE_COOKIE,
  243           NGM_BRIDGE_RESET,
  244           "reset",
  245           NULL,
  246           NULL
  247         },
  248         {
  249           NGM_BRIDGE_COOKIE,
  250           NGM_BRIDGE_GET_STATS,
  251           "getstats",
  252           &ng_parse_uint32_type,
  253           &ng_bridge_stats_type
  254         },
  255         {
  256           NGM_BRIDGE_COOKIE,
  257           NGM_BRIDGE_CLR_STATS,
  258           "clrstats",
  259           &ng_parse_uint32_type,
  260           NULL
  261         },
  262         {
  263           NGM_BRIDGE_COOKIE,
  264           NGM_BRIDGE_GETCLR_STATS,
  265           "getclrstats",
  266           &ng_parse_uint32_type,
  267           &ng_bridge_stats_type
  268         },
  269         {
  270           NGM_BRIDGE_COOKIE,
  271           NGM_BRIDGE_GET_TABLE,
  272           "gettable",
  273           NULL,
  274           &ng_bridge_host_ary_type
  275         },
  276         {
  277           NGM_BRIDGE_COOKIE,
  278           NGM_BRIDGE_SET_PERSISTENT,
  279           "setpersistent",
  280           NULL,
  281           NULL
  282         },
  283         { 0 }
  284 };
  285 
  286 /* Node type descriptor */
  287 static struct ng_type ng_bridge_typestruct = {
  288         .version =      NG_ABI_VERSION,
  289         .name =         NG_BRIDGE_NODE_TYPE,
  290         .constructor =  ng_bridge_constructor,
  291         .rcvmsg =       ng_bridge_rcvmsg,
  292         .shutdown =     ng_bridge_shutdown,
  293         .newhook =      ng_bridge_newhook,
  294         .rcvdata =      ng_bridge_rcvdata,
  295         .disconnect =   ng_bridge_disconnect,
  296         .cmdlist =      ng_bridge_cmdlist,
  297 };
  298 NETGRAPH_INIT(bridge, &ng_bridge_typestruct);
  299 
  300 /******************************************************************
  301                     NETGRAPH NODE METHODS
  302 ******************************************************************/
  303 
  304 /*
  305  * Node constructor
  306  */
  307 static int
  308 ng_bridge_constructor(node_p node)
  309 {
  310         priv_p priv;
  311 
  312         /* Allocate and initialize private info */
  313         priv = malloc(sizeof(*priv), M_NETGRAPH_BRIDGE, M_WAITOK | M_ZERO);
  314         ng_callout_init(&priv->timer);
  315 
  316         /* Allocate and initialize hash table, etc. */
  317         priv->tab = malloc(MIN_BUCKETS * sizeof(*priv->tab),
  318             M_NETGRAPH_BRIDGE, M_WAITOK | M_ZERO);
  319         priv->numBuckets = MIN_BUCKETS;
  320         priv->hashMask = MIN_BUCKETS - 1;
  321         priv->conf.debugLevel = 1;
  322         priv->conf.loopTimeout = DEFAULT_LOOP_TIMEOUT;
  323         priv->conf.maxStaleness = DEFAULT_MAX_STALENESS;
  324         priv->conf.minStableAge = DEFAULT_MIN_STABLE_AGE;
  325 
  326         /*
  327          * This node has all kinds of stuff that could be screwed by SMP.
  328          * Until it gets it's own internal protection, we go through in 
  329          * single file. This could hurt a machine bridging beteen two 
  330          * GB ethernets so it should be fixed. 
  331          * When it's fixed the process SHOULD NOT SLEEP, spinlocks please!
  332          * (and atomic ops )
  333          */
  334         NG_NODE_FORCE_WRITER(node);
  335         NG_NODE_SET_PRIVATE(node, priv);
  336         priv->node = node;
  337 
  338         /* Start timer; timer is always running while node is alive */
  339         ng_callout(&priv->timer, node, NULL, hz, ng_bridge_timeout, NULL, 0);
  340 
  341         /* Done */
  342         return (0);
  343 }
  344 
  345 /*
  346  * Method for attaching a new hook
  347  */
  348 static  int
  349 ng_bridge_newhook(node_p node, hook_p hook, const char *name)
  350 {
  351         const priv_p priv = NG_NODE_PRIVATE(node);
  352 
  353         /* Check for a link hook */
  354         if (strncmp(name, NG_BRIDGE_HOOK_LINK_PREFIX,
  355             strlen(NG_BRIDGE_HOOK_LINK_PREFIX)) == 0) {
  356                 const char *cp;
  357                 char *eptr;
  358                 u_long linkNum;
  359 
  360                 cp = name + strlen(NG_BRIDGE_HOOK_LINK_PREFIX);
  361                 if (!isdigit(*cp) || (cp[0] == '' && cp[1] != '\0'))
  362                         return (EINVAL);
  363                 linkNum = strtoul(cp, &eptr, 10);
  364                 if (*eptr != '\0' || linkNum >= NG_BRIDGE_MAX_LINKS)
  365                         return (EINVAL);
  366                 if (priv->links[linkNum] != NULL)
  367                         return (EISCONN);
  368                 priv->links[linkNum] = malloc(sizeof(*priv->links[linkNum]),
  369                     M_NETGRAPH_BRIDGE, M_NOWAIT|M_ZERO);
  370                 if (priv->links[linkNum] == NULL)
  371                         return (ENOMEM);
  372                 priv->links[linkNum]->hook = hook;
  373                 NG_HOOK_SET_PRIVATE(hook, (void *)linkNum);
  374                 priv->numLinks++;
  375                 return (0);
  376         }
  377 
  378         /* Unknown hook name */
  379         return (EINVAL);
  380 }
  381 
  382 /*
  383  * Receive a control message
  384  */
  385 static int
  386 ng_bridge_rcvmsg(node_p node, item_p item, hook_p lasthook)
  387 {
  388         const priv_p priv = NG_NODE_PRIVATE(node);
  389         struct ng_mesg *resp = NULL;
  390         int error = 0;
  391         struct ng_mesg *msg;
  392 
  393         NGI_GET_MSG(item, msg);
  394         switch (msg->header.typecookie) {
  395         case NGM_BRIDGE_COOKIE:
  396                 switch (msg->header.cmd) {
  397                 case NGM_BRIDGE_GET_CONFIG:
  398                     {
  399                         struct ng_bridge_config *conf;
  400 
  401                         NG_MKRESPONSE(resp, msg,
  402                             sizeof(struct ng_bridge_config), M_NOWAIT);
  403                         if (resp == NULL) {
  404                                 error = ENOMEM;
  405                                 break;
  406                         }
  407                         conf = (struct ng_bridge_config *)resp->data;
  408                         *conf = priv->conf;     /* no sanity checking needed */
  409                         break;
  410                     }
  411                 case NGM_BRIDGE_SET_CONFIG:
  412                     {
  413                         struct ng_bridge_config *conf;
  414                         int i;
  415 
  416                         if (msg->header.arglen
  417                             != sizeof(struct ng_bridge_config)) {
  418                                 error = EINVAL;
  419                                 break;
  420                         }
  421                         conf = (struct ng_bridge_config *)msg->data;
  422                         priv->conf = *conf;
  423                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++)
  424                                 priv->conf.ipfw[i] = !!priv->conf.ipfw[i];
  425                         break;
  426                     }
  427                 case NGM_BRIDGE_RESET:
  428                     {
  429                         int i;
  430 
  431                         /* Flush all entries in the hash table */
  432                         ng_bridge_remove_hosts(priv, -1);
  433 
  434                         /* Reset all loop detection counters and stats */
  435                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++) {
  436                                 if (priv->links[i] == NULL)
  437                                         continue;
  438                                 priv->links[i]->loopCount = 0;
  439                                 bzero(&priv->links[i]->stats,
  440                                     sizeof(priv->links[i]->stats));
  441                         }
  442                         break;
  443                     }
  444                 case NGM_BRIDGE_GET_STATS:
  445                 case NGM_BRIDGE_CLR_STATS:
  446                 case NGM_BRIDGE_GETCLR_STATS:
  447                     {
  448                         struct ng_bridge_link *link;
  449                         int linkNum;
  450 
  451                         /* Get link number */
  452                         if (msg->header.arglen != sizeof(u_int32_t)) {
  453                                 error = EINVAL;
  454                                 break;
  455                         }
  456                         linkNum = *((u_int32_t *)msg->data);
  457                         if (linkNum < 0 || linkNum >= NG_BRIDGE_MAX_LINKS) {
  458                                 error = EINVAL;
  459                                 break;
  460                         }
  461                         if ((link = priv->links[linkNum]) == NULL) {
  462                                 error = ENOTCONN;
  463                                 break;
  464                         }
  465 
  466                         /* Get/clear stats */
  467                         if (msg->header.cmd != NGM_BRIDGE_CLR_STATS) {
  468                                 NG_MKRESPONSE(resp, msg,
  469                                     sizeof(link->stats), M_NOWAIT);
  470                                 if (resp == NULL) {
  471                                         error = ENOMEM;
  472                                         break;
  473                                 }
  474                                 bcopy(&link->stats,
  475                                     resp->data, sizeof(link->stats));
  476                         }
  477                         if (msg->header.cmd != NGM_BRIDGE_GET_STATS)
  478                                 bzero(&link->stats, sizeof(link->stats));
  479                         break;
  480                     }
  481                 case NGM_BRIDGE_GET_TABLE:
  482                     {
  483                         struct ng_bridge_host_ary *ary;
  484                         struct ng_bridge_hent *hent;
  485                         int i = 0, bucket;
  486 
  487                         NG_MKRESPONSE(resp, msg, sizeof(*ary)
  488                             + (priv->numHosts * sizeof(*ary->hosts)), M_NOWAIT);
  489                         if (resp == NULL) {
  490                                 error = ENOMEM;
  491                                 break;
  492                         }
  493                         ary = (struct ng_bridge_host_ary *)resp->data;
  494                         ary->numHosts = priv->numHosts;
  495                         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  496                                 SLIST_FOREACH(hent, &priv->tab[bucket], next)
  497                                         ary->hosts[i++] = hent->host;
  498                         }
  499                         break;
  500                     }
  501                 case NGM_BRIDGE_SET_PERSISTENT:
  502                     {
  503                         priv->persistent = 1;
  504                         break;
  505                     }
  506                 default:
  507                         error = EINVAL;
  508                         break;
  509                 }
  510                 break;
  511         default:
  512                 error = EINVAL;
  513                 break;
  514         }
  515 
  516         /* Done */
  517         NG_RESPOND_MSG(error, node, item, resp);
  518         NG_FREE_MSG(msg);
  519         return (error);
  520 }
  521 
  522 /*
  523  * Receive data on a hook
  524  */
  525 static int
  526 ng_bridge_rcvdata(hook_p hook, item_p item)
  527 {
  528         const node_p node = NG_HOOK_NODE(hook);
  529         const priv_p priv = NG_NODE_PRIVATE(node);
  530         struct ng_bridge_host *host;
  531         struct ng_bridge_link *link;
  532         struct ether_header *eh;
  533         int error = 0, linkNum, linksSeen;
  534         int manycast;
  535         struct mbuf *m;
  536         struct ng_bridge_link *firstLink;
  537 
  538         NGI_GET_M(item, m);
  539         /* Get link number */
  540         linkNum = (intptr_t)NG_HOOK_PRIVATE(hook);
  541         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
  542             ("%s: linkNum=%u", __func__, linkNum));
  543         link = priv->links[linkNum];
  544         KASSERT(link != NULL, ("%s: link%d null", __func__, linkNum));
  545 
  546         /* Sanity check packet and pull up header */
  547         if (m->m_pkthdr.len < ETHER_HDR_LEN) {
  548                 link->stats.recvRunts++;
  549                 NG_FREE_ITEM(item);
  550                 NG_FREE_M(m);
  551                 return (EINVAL);
  552         }
  553         if (m->m_len < ETHER_HDR_LEN && !(m = m_pullup(m, ETHER_HDR_LEN))) {
  554                 link->stats.memoryFailures++;
  555                 NG_FREE_ITEM(item);
  556                 return (ENOBUFS);
  557         }
  558         eh = mtod(m, struct ether_header *);
  559         if ((eh->ether_shost[0] & 1) != 0) {
  560                 link->stats.recvInvalid++;
  561                 NG_FREE_ITEM(item);
  562                 NG_FREE_M(m);
  563                 return (EINVAL);
  564         }
  565 
  566         /* Is link disabled due to a loopback condition? */
  567         if (link->loopCount != 0) {
  568                 link->stats.loopDrops++;
  569                 NG_FREE_ITEM(item);
  570                 NG_FREE_M(m);
  571                 return (ELOOP);         /* XXX is this an appropriate error? */
  572         }
  573 
  574         /* Update stats */
  575         link->stats.recvPackets++;
  576         link->stats.recvOctets += m->m_pkthdr.len;
  577         if ((manycast = (eh->ether_dhost[0] & 1)) != 0) {
  578                 if (ETHER_EQUAL(eh->ether_dhost, ng_bridge_bcast_addr)) {
  579                         link->stats.recvBroadcasts++;
  580                         manycast = 2;
  581                 } else
  582                         link->stats.recvMulticasts++;
  583         }
  584 
  585         /* Look up packet's source Ethernet address in hashtable */
  586         if ((host = ng_bridge_get(priv, eh->ether_shost)) != NULL) {
  587 
  588                 /* Update time since last heard from this host */
  589                 host->staleness = 0;
  590 
  591                 /* Did host jump to a different link? */
  592                 if (host->linkNum != linkNum) {
  593 
  594                         /*
  595                          * If the host's old link was recently established
  596                          * on the old link and it's already jumped to a new
  597                          * link, declare a loopback condition.
  598                          */
  599                         if (host->age < priv->conf.minStableAge) {
  600 
  601                                 /* Log the problem */
  602                                 if (priv->conf.debugLevel >= 2) {
  603                                         struct ifnet *ifp = m->m_pkthdr.rcvif;
  604                                         char suffix[32];
  605 
  606                                         if (ifp != NULL)
  607                                                 snprintf(suffix, sizeof(suffix),
  608                                                     " (%s)", ifp->if_xname);
  609                                         else
  610                                                 *suffix = '\0';
  611                                         log(LOG_WARNING, "ng_bridge: %s:"
  612                                             " loopback detected on %s%s\n",
  613                                             ng_bridge_nodename(node),
  614                                             NG_HOOK_NAME(hook), suffix);
  615                                 }
  616 
  617                                 /* Mark link as linka non grata */
  618                                 link->loopCount = priv->conf.loopTimeout;
  619                                 link->stats.loopDetects++;
  620 
  621                                 /* Forget all hosts on this link */
  622                                 ng_bridge_remove_hosts(priv, linkNum);
  623 
  624                                 /* Drop packet */
  625                                 link->stats.loopDrops++;
  626                                 NG_FREE_ITEM(item);
  627                                 NG_FREE_M(m);
  628                                 return (ELOOP);         /* XXX appropriate? */
  629                         }
  630 
  631                         /* Move host over to new link */
  632                         host->linkNum = linkNum;
  633                         host->age = 0;
  634                 }
  635         } else {
  636                 if (!ng_bridge_put(priv, eh->ether_shost, linkNum)) {
  637                         link->stats.memoryFailures++;
  638                         NG_FREE_ITEM(item);
  639                         NG_FREE_M(m);
  640                         return (ENOMEM);
  641                 }
  642         }
  643 
  644         /* Run packet through ipfw processing, if enabled */
  645 #if 0
  646         if (priv->conf.ipfw[linkNum] && V_fw_enable && V_ip_fw_chk_ptr != NULL) {
  647                 /* XXX not implemented yet */
  648         }
  649 #endif
  650 
  651         /*
  652          * If unicast and destination host known, deliver to host's link,
  653          * unless it is the same link as the packet came in on.
  654          */
  655         if (!manycast) {
  656 
  657                 /* Determine packet destination link */
  658                 if ((host = ng_bridge_get(priv, eh->ether_dhost)) != NULL) {
  659                         struct ng_bridge_link *const destLink
  660                             = priv->links[host->linkNum];
  661 
  662                         /* If destination same as incoming link, do nothing */
  663                         KASSERT(destLink != NULL,
  664                             ("%s: link%d null", __func__, host->linkNum));
  665                         if (destLink == link) {
  666                                 NG_FREE_ITEM(item);
  667                                 NG_FREE_M(m);
  668                                 return (0);
  669                         }
  670 
  671                         /* Deliver packet out the destination link */
  672                         destLink->stats.xmitPackets++;
  673                         destLink->stats.xmitOctets += m->m_pkthdr.len;
  674                         NG_FWD_NEW_DATA(error, item, destLink->hook, m);
  675                         return (error);
  676                 }
  677 
  678                 /* Destination host is not known */
  679                 link->stats.recvUnknown++;
  680         }
  681 
  682         /* Distribute unknown, multicast, broadcast pkts to all other links */
  683         firstLink = NULL;
  684         for (linkNum = linksSeen = 0; linksSeen <= priv->numLinks; linkNum++) {
  685                 struct ng_bridge_link *destLink;
  686                 struct mbuf *m2 = NULL;
  687 
  688                 /*
  689                  * If we have checked all the links then now
  690                  * send the original on its reserved link
  691                  */
  692                 if (linksSeen == priv->numLinks) {
  693                         /* If we never saw a good link, leave. */
  694                         if (firstLink == NULL) {
  695                                 NG_FREE_ITEM(item);
  696                                 NG_FREE_M(m);
  697                                 return (0);
  698                         }       
  699                         destLink = firstLink;
  700                 } else {
  701                         destLink = priv->links[linkNum];
  702                         if (destLink != NULL)
  703                                 linksSeen++;
  704                         /* Skip incoming link and disconnected links */
  705                         if (destLink == NULL || destLink == link) {
  706                                 continue;
  707                         }
  708                         if (firstLink == NULL) {
  709                                 /*
  710                                  * This is the first usable link we have found.
  711                                  * Reserve it for the originals.
  712                                  * If we never find another we save a copy.
  713                                  */
  714                                 firstLink = destLink;
  715                                 continue;
  716                         }
  717 
  718                         /*
  719                          * It's usable link but not the reserved (first) one.
  720                          * Copy mbuf info for sending.
  721                          */
  722                         m2 = m_dup(m, M_DONTWAIT);      /* XXX m_copypacket() */
  723                         if (m2 == NULL) {
  724                                 link->stats.memoryFailures++;
  725                                 NG_FREE_ITEM(item);
  726                                 NG_FREE_M(m);
  727                                 return (ENOBUFS);
  728                         }
  729                 }
  730 
  731                 /* Update stats */
  732                 destLink->stats.xmitPackets++;
  733                 destLink->stats.xmitOctets += m->m_pkthdr.len;
  734                 switch (manycast) {
  735                 case 0:                                 /* unicast */
  736                         break;
  737                 case 1:                                 /* multicast */
  738                         destLink->stats.xmitMulticasts++;
  739                         break;
  740                 case 2:                                 /* broadcast */
  741                         destLink->stats.xmitBroadcasts++;
  742                         break;
  743                 }
  744 
  745                 /* Send packet */
  746                 if (destLink == firstLink) { 
  747                         /*
  748                          * If we've sent all the others, send the original
  749                          * on the first link we found.
  750                          */
  751                         NG_FWD_NEW_DATA(error, item, destLink->hook, m);
  752                         break; /* always done last - not really needed. */
  753                 } else {
  754                         NG_SEND_DATA_ONLY(error, destLink->hook, m2);
  755                 }
  756         }
  757         return (error);
  758 }
  759 
  760 /*
  761  * Shutdown node
  762  */
  763 static int
  764 ng_bridge_shutdown(node_p node)
  765 {
  766         const priv_p priv = NG_NODE_PRIVATE(node);
  767 
  768         /*
  769          * Shut down everything including the timer.  Even if the
  770          * callout has already been dequeued and is about to be
  771          * run, ng_bridge_timeout() won't be fired as the node
  772          * is already marked NGF_INVALID, so we're safe to free
  773          * the node now.
  774          */
  775         KASSERT(priv->numLinks == 0 && priv->numHosts == 0,
  776             ("%s: numLinks=%d numHosts=%d",
  777             __func__, priv->numLinks, priv->numHosts));
  778         ng_uncallout(&priv->timer, node);
  779         NG_NODE_SET_PRIVATE(node, NULL);
  780         NG_NODE_UNREF(node);
  781         free(priv->tab, M_NETGRAPH_BRIDGE);
  782         free(priv, M_NETGRAPH_BRIDGE);
  783         return (0);
  784 }
  785 
  786 /*
  787  * Hook disconnection.
  788  */
  789 static int
  790 ng_bridge_disconnect(hook_p hook)
  791 {
  792         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  793         int linkNum;
  794 
  795         /* Get link number */
  796         linkNum = (intptr_t)NG_HOOK_PRIVATE(hook);
  797         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
  798             ("%s: linkNum=%u", __func__, linkNum));
  799 
  800         /* Remove all hosts associated with this link */
  801         ng_bridge_remove_hosts(priv, linkNum);
  802 
  803         /* Free associated link information */
  804         KASSERT(priv->links[linkNum] != NULL, ("%s: no link", __func__));
  805         free(priv->links[linkNum], M_NETGRAPH_BRIDGE);
  806         priv->links[linkNum] = NULL;
  807         priv->numLinks--;
  808 
  809         /* If no more hooks, go away */
  810         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  811             && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))
  812             && !priv->persistent) {
  813                 ng_rmnode_self(NG_HOOK_NODE(hook));
  814         }
  815         return (0);
  816 }
  817 
  818 /******************************************************************
  819                     HASH TABLE FUNCTIONS
  820 ******************************************************************/
  821 
  822 /*
  823  * Hash algorithm
  824  */
  825 #define HASH(addr,mask)         ( (((const u_int16_t *)(addr))[0]       \
  826                                  ^ ((const u_int16_t *)(addr))[1]       \
  827                                  ^ ((const u_int16_t *)(addr))[2]) & (mask) )
  828 
  829 /*
  830  * Find a host entry in the table.
  831  */
  832 static struct ng_bridge_host *
  833 ng_bridge_get(priv_p priv, const u_char *addr)
  834 {
  835         const int bucket = HASH(addr, priv->hashMask);
  836         struct ng_bridge_hent *hent;
  837 
  838         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  839                 if (ETHER_EQUAL(hent->host.addr, addr))
  840                         return (&hent->host);
  841         }
  842         return (NULL);
  843 }
  844 
  845 /*
  846  * Add a new host entry to the table. This assumes the host doesn't
  847  * already exist in the table. Returns 1 on success, 0 if there
  848  * was a memory allocation failure.
  849  */
  850 static int
  851 ng_bridge_put(priv_p priv, const u_char *addr, int linkNum)
  852 {
  853         const int bucket = HASH(addr, priv->hashMask);
  854         struct ng_bridge_hent *hent;
  855 
  856 #ifdef INVARIANTS
  857         /* Assert that entry does not already exist in hashtable */
  858         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  859                 KASSERT(!ETHER_EQUAL(hent->host.addr, addr),
  860                     ("%s: entry %6D exists in table", __func__, addr, ":"));
  861         }
  862 #endif
  863 
  864         /* Allocate and initialize new hashtable entry */
  865         hent = malloc(sizeof(*hent), M_NETGRAPH_BRIDGE, M_NOWAIT);
  866         if (hent == NULL)
  867                 return (0);
  868         bcopy(addr, hent->host.addr, ETHER_ADDR_LEN);
  869         hent->host.linkNum = linkNum;
  870         hent->host.staleness = 0;
  871         hent->host.age = 0;
  872 
  873         /* Add new element to hash bucket */
  874         SLIST_INSERT_HEAD(&priv->tab[bucket], hent, next);
  875         priv->numHosts++;
  876 
  877         /* Resize table if necessary */
  878         ng_bridge_rehash(priv);
  879         return (1);
  880 }
  881 
  882 /*
  883  * Resize the hash table. We try to maintain the number of buckets
  884  * such that the load factor is in the range 0.25 to 1.0.
  885  *
  886  * If we can't get the new memory then we silently fail. This is OK
  887  * because things will still work and we'll try again soon anyway.
  888  */
  889 static void
  890 ng_bridge_rehash(priv_p priv)
  891 {
  892         struct ng_bridge_bucket *newTab;
  893         int oldBucket, newBucket;
  894         int newNumBuckets;
  895         u_int newMask;
  896 
  897         /* Is table too full or too empty? */
  898         if (priv->numHosts > priv->numBuckets
  899             && (priv->numBuckets << 1) <= MAX_BUCKETS)
  900                 newNumBuckets = priv->numBuckets << 1;
  901         else if (priv->numHosts < (priv->numBuckets >> 2)
  902             && (priv->numBuckets >> 2) >= MIN_BUCKETS)
  903                 newNumBuckets = priv->numBuckets >> 2;
  904         else
  905                 return;
  906         newMask = newNumBuckets - 1;
  907 
  908         /* Allocate and initialize new table */
  909         newTab = malloc(newNumBuckets * sizeof(*newTab),
  910             M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  911         if (newTab == NULL)
  912                 return;
  913 
  914         /* Move all entries from old table to new table */
  915         for (oldBucket = 0; oldBucket < priv->numBuckets; oldBucket++) {
  916                 struct ng_bridge_bucket *const oldList = &priv->tab[oldBucket];
  917 
  918                 while (!SLIST_EMPTY(oldList)) {
  919                         struct ng_bridge_hent *const hent
  920                             = SLIST_FIRST(oldList);
  921 
  922                         SLIST_REMOVE_HEAD(oldList, next);
  923                         newBucket = HASH(hent->host.addr, newMask);
  924                         SLIST_INSERT_HEAD(&newTab[newBucket], hent, next);
  925                 }
  926         }
  927 
  928         /* Replace old table with new one */
  929         if (priv->conf.debugLevel >= 3) {
  930                 log(LOG_INFO, "ng_bridge: %s: table size %d -> %d\n",
  931                     ng_bridge_nodename(priv->node),
  932                     priv->numBuckets, newNumBuckets);
  933         }
  934         free(priv->tab, M_NETGRAPH_BRIDGE);
  935         priv->numBuckets = newNumBuckets;
  936         priv->hashMask = newMask;
  937         priv->tab = newTab;
  938         return;
  939 }
  940 
  941 /******************************************************************
  942                     MISC FUNCTIONS
  943 ******************************************************************/
  944 
  945 /*
  946  * Remove all hosts associated with a specific link from the hashtable.
  947  * If linkNum == -1, then remove all hosts in the table.
  948  */
  949 static void
  950 ng_bridge_remove_hosts(priv_p priv, int linkNum)
  951 {
  952         int bucket;
  953 
  954         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  955                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
  956 
  957                 while (*hptr != NULL) {
  958                         struct ng_bridge_hent *const hent = *hptr;
  959 
  960                         if (linkNum == -1 || hent->host.linkNum == linkNum) {
  961                                 *hptr = SLIST_NEXT(hent, next);
  962                                 free(hent, M_NETGRAPH_BRIDGE);
  963                                 priv->numHosts--;
  964                         } else
  965                                 hptr = &SLIST_NEXT(hent, next);
  966                 }
  967         }
  968 }
  969 
  970 /*
  971  * Handle our once-per-second timeout event. We do two things:
  972  * we decrement link->loopCount for those links being muted due to
  973  * a detected loopback condition, and we remove any hosts from
  974  * the hashtable whom we haven't heard from in a long while.
  975  */
  976 static void
  977 ng_bridge_timeout(node_p node, hook_p hook, void *arg1, int arg2)
  978 {
  979         const priv_p priv = NG_NODE_PRIVATE(node);
  980         int bucket;
  981         int counter = 0;
  982         int linkNum;
  983 
  984         /* Update host time counters and remove stale entries */
  985         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  986                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
  987 
  988                 while (*hptr != NULL) {
  989                         struct ng_bridge_hent *const hent = *hptr;
  990 
  991                         /* Make sure host's link really exists */
  992                         KASSERT(priv->links[hent->host.linkNum] != NULL,
  993                             ("%s: host %6D on nonexistent link %d\n",
  994                             __func__, hent->host.addr, ":",
  995                             hent->host.linkNum));
  996 
  997                         /* Remove hosts we haven't heard from in a while */
  998                         if (++hent->host.staleness >= priv->conf.maxStaleness) {
  999                                 *hptr = SLIST_NEXT(hent, next);
 1000                                 free(hent, M_NETGRAPH_BRIDGE);
 1001                                 priv->numHosts--;
 1002                         } else {
 1003                                 if (hent->host.age < 0xffff)
 1004                                         hent->host.age++;
 1005                                 hptr = &SLIST_NEXT(hent, next);
 1006                                 counter++;
 1007                         }
 1008                 }
 1009         }
 1010         KASSERT(priv->numHosts == counter,
 1011             ("%s: hosts: %d != %d", __func__, priv->numHosts, counter));
 1012 
 1013         /* Decrease table size if necessary */
 1014         ng_bridge_rehash(priv);
 1015 
 1016         /* Decrease loop counter on muted looped back links */
 1017         for (counter = linkNum = 0; linkNum < NG_BRIDGE_MAX_LINKS; linkNum++) {
 1018                 struct ng_bridge_link *const link = priv->links[linkNum];
 1019 
 1020                 if (link != NULL) {
 1021                         if (link->loopCount != 0) {
 1022                                 link->loopCount--;
 1023                                 if (link->loopCount == 0
 1024                                     && priv->conf.debugLevel >= 2) {
 1025                                         log(LOG_INFO, "ng_bridge: %s:"
 1026                                             " restoring looped back link%d\n",
 1027                                             ng_bridge_nodename(node), linkNum);
 1028                                 }
 1029                         }
 1030                         counter++;
 1031                 }
 1032         }
 1033         KASSERT(priv->numLinks == counter,
 1034             ("%s: links: %d != %d", __func__, priv->numLinks, counter));
 1035 
 1036         /* Register a new timeout, keeping the existing node reference */
 1037         ng_callout(&priv->timer, node, NULL, hz, ng_bridge_timeout, NULL, 0);
 1038 }
 1039 
 1040 /*
 1041  * Return node's "name", even if it doesn't have one.
 1042  */
 1043 static const char *
 1044 ng_bridge_nodename(node_p node)
 1045 {
 1046         static char name[NG_NODESIZ];
 1047 
 1048         if (NG_NODE_NAME(node) != NULL)
 1049                 snprintf(name, sizeof(name), "%s", NG_NODE_NAME(node));
 1050         else
 1051                 snprintf(name, sizeof(name), "[%x]", ng_node2ID(node));
 1052         return name;
 1053 }
 1054 

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